The present invention relates to an electrical heating arrangement in a motor vehicle having an electrical network including a power generator, a regulator for the generator, a battery, consuming devices connected to the battery, a battery charge indicator, a heating element and switching means for connecting, in one switching position, the power generator to the heating element and, in another switching position, the power generator to the battery.
It is conventional to heat passenger space in a motor vehicle by means of cooling water of the engine. At low outdoor temperatures it takes relatively long time to heat the passenger space to a desired temperature.
In order to speed up the temperature rise in the passenger space, it is possible by means of the generator and heater elements to utilize power supplied by the generator to accelerate the heating to the desired temperature.
An electrical heating system for motor vehicles of this kind is known for example from the DE-OS 35 09 073. It describes a heating arrangement wherein a number of heating resistors is connected to the plus terminal of the generator or of the battery to utilize excessive direct current supplied by the generator to the battery which in turn power supplies the electrical consuming devices. This arrangement also includes a control device which prevents a discharge of the battery due to the switchover of the generator power for the heating purposes.
This known electrical heating arrangement has several disadvantages. First, only the excessive part of the generated power is employed for the heating of the motor vehicles and therefore the heating efficiency is not very effective. Secondly, there is no possibility to indicate failures in the heating and power supply arrangement, for example the interruption of the battery charging cable or an interruption of the cable connecting the generator with the heating element.